1. Field of the Invention
This invention pertains to an intravenous delivery system, and to a formulation chamber containing a drug delivery device. The invention relates also to a method of parenterally (e.g., intravenously) administering a drug, and to a method of forming the drug during parenteral administration.
2. Description of the Prior Art
The parenteral administration of medical liquids is an established clinical practice. The liquids are administered particularly intravenously, and the practice is used extensively as an integral part of the daily treatment of medical and surgical patients. The liquids commonly administered include blood and blood substitutes, dextrose solutions, electrolyte solutions and saline. Generally the liquids are administered from an intravenous (IV) delivery system having a container suspended above the patient, with the liquid flowing through a catheter hypodermic needle set to the patient.
The administration of liquids intravenously is a valuable and important component that contributes to the optimal care of the patient. However, it does not easily provide a satisfactory means and method for administering concomitantly therewith a beneficial agent, such as a drug. Beneficial agents have been administered intravenously by one of the following methods: (1) temporarily removing or disconnecting the IV system administering the agent to the patient, then administering the drug by hypodermic injection (either into the disconnected IV line or directly into the vein of the patient), followed by reinserting the IV system into the patient; (2) adding the agent to the IV liquid in the container which is then carried by the flow of the liquid to the patient; (3) adding the agent to an IV liquid in a secondary container (called a partial fill) that is then connected to the primary IV line; (4) adding the agent to an IV liquid contained in a piggyback vial which is subsequently connected to the primary IV line; or (5) administering intravenously an IV liquid containing a beneficial agent using a pump. While these techniques are used, they have major disadvantages. For example, they often require preformulation of the agent medication by the hospital pharmacist or nurse. They often require separate connections for joining the drug flow line to the primary intravenous line which further complicates intravenous administration. The use of pumps can produce pressures that can vary at the delivery site and the pressure can give rise to thrombosis. Finally, the rate of agent delivery to the patient often is unknown as it is not rate-controlled agent delivery but rather is dependent on the rate of IV fluid flow.
Eckenhoff et al in U.S. Pat. No. 4,474,575 discloses an IV administration set (FIG. 6) providing excellent control over the rate at which beneficial agent is administered to a patient. Unfortunately, the device disclosed by Eckenhoff et al is not easily adapted to a conventional IV administration set which typically includes an IV fluid container, a drip chamber for visually determining the rate of IV fluid flow from the container, a bacterial filter, and terminating in an adaptor-needle assembly that is inserted into the vein of a warm-blooded animal (e.g., a human patient). In order to adapt the Eckenhoff device to a conventional IV administration set, a secondary IV fluid line must be connected into the primary IV line which complicates the intravenous administration.
In response to these difficulties, Theeuwes in U.S. Pat. No. 4,511,353 (and in related U.S. Pat. Nos. 4,740,103; 4,740,200 and 4,740,201) developed a formulation chamber adapted to easily fit into a conventional IV administration set. The formulation chamber is adapted to contain a drug delivery device for delivering a drug or other beneficial agent into the IV fluid flowing through the formulation chamber. The drug delivery device within the formulation chamber is selected from elementary osmotic pumps (FIGS. 2a, 2b, 9, 10, and 11) release rate controlling membranes surrounding a drug reservoir (FIGS. 3-5, 12 and 13) and a polymer matrix containing the drug, the drug being able to diffuse through the matrix into the flowing IV fluid (FIGS. 6-8). All of these devices provide the advantage of controlling the rate at which the drug or other beneficial agent is released into the IV fluid, independently of the rate at which the IV fluid flows through the formulation chamber.
While these devices represent a significant advance in the art, there remains a need for a drug formulation chamber which can provide an even higher degree of control over the rate at which a beneficial agent, such as a drug, is introduced into an IV fluid flowing in a standard IV administration set.
Accordingly, it is an object of this invention to provide a parenteral (e.g., intravenous) delivery system which delivers an agent at a controlled rate into a flowing parenteral fluid for optimizing the care of an animal (e.g., a human) whose prognosis benefits from parenteral delivery.
It is another object of the invention to provide an intravenous delivery system having an agent formulation chamber which contains an agent delivery device for admitting agent at a rate controlled by the delivery device, instead of the flow rate of intravenous fluid through the system, for optimizing the care of a patient on intravenous delivery.
Another object of the invention is to provide an intravenous therapeutic system including a container of an intravenous medical fluid and a drug formulation chamber which contains an agent delivery device which can deliver drug, to a flowing IV fluid, at a rate which is variable and which is accurately controlled by the device.